"I have a friend that was a seasoned street fighter that was interested in what I was taking for martial arts; so, I asked him to attack (grab) and I entered in, then told him to try and elbow me in the kidney...I then cut down on the inside of the striking elbow and did tenkan and then executed irmi nage movement...stopping right as I broke his balance so that he didn't fall. His comment, "@#$%, that could really hurt if you did that to someone on concrete!"

Next time you work with your friend, just ask him to attack, dont tell him how and where to attack! Let him attack with his own intentions, fullspeed, wherever and however he wants, without you knowing what he is going to do!